This invention relates to an improvement of a liquid crystal projector. A liquid crystal projector is generally used to display a television picture by means of, for example, a transparent TN type liquid crystal display panel, and to project said picture on the screen in an enlarged form.
The liquid crystal projector usually comprises a lamp set on the backside of the liquid crystal display panel. The lamp illuminates the backside of the liquid crystal display panel to brighten an image to be displayed. The image is enlarged by means of a projection lens system, thereby casting an enlarged picture on the screen set ahead.
As is well known, the TN type liquid crystal display panel has a specific viewing angle. The direction which an image displayed on the panel can be observed in the brightest form, is at a suitable viewing angle to the front side of the display panel. FIG. 1 illustrates the view field angle of the TN type liquid crystal display panel 11. The suitable viewing angle K is obtained by inclining Y axis toward X axis by angle .alpha. and inclining Z axis toward X-Y plane by angle .beta..
However, if, as in the conventional liquid crystal projector, the liquid crystal display panel is vertically set in parallel with the screen plane, then the suitable viewing angle of the liquid crystal display panel fails to coincide with the optical axis of the lens system of the liquid crystal projector, thereby obstructing the brightness and contrast of an image projected on the screen. To be free of said drawback, the conventional liquid crystal projector is so designed as to cause the liquid crystal display panel to face the screen in the form inclined to the perpendicular line of the optical axis by a proper view field angle. This arrangement can project the image of the liquid crystal display panel onto the screen under the condition of the highest brightness and best contrast.
Nevertheless, the conventional liquid crystal projector is accompanied with the drawbacks that since the liquid crystal display panel is inclined, variations arise in the distances between the points on the outer periphery of an image appearing on the liquid crystal display panel and the corresponding points on the outer periphery of an image cast on the screen; and consequently an image projected on the screen is warped to an extent corresponding to the inclination angle of said liquid crystal display panel. This event constituted the prominent defect of the conventional liquid crystal projector.